Electrical clock system



March l, 1932- M. H. sHoENBERG 1,847,313

ELECTRICAL CLOCK SYSTEM Filed Feb. 15. 1927 2 sheets-sheet 1.

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/ A TTORNE YS March l, 1932. M. H. sHoENBERG ELECTRICAL CLOCK SYSTEM Filed Feb. l5, 1927 2 Sheets-Sheet 2 Patented Mar. 1, 1932 UNITED-STATES OFFICE MILTON II. sIIoENBERG, oN'sAN FRANCISCO, CALIFORNIA, AssIGNoIt, BY MEsNE As-r SIGNMENTS, TO A. F. MUNDY, OF LOS AN'GELES, GALIFORNIA.`

`ELECTRICAL CLOCK SYSTEM- i Application mea February 15, 1927. Serial No. 168,412.

This 'invention relates generally to an electrical clock system in which aplurallty of clocks are controlled from a remote point by a master clock. I

It is an object of this invention to devise an electrical clock system which isespecially adapted to be used in conjunction with a source of alternating current.

- It is a further object of this invention toy 1() devise anv electrical clock system -in which means is provided for bringing the dependent clocks of the ysystem into synchronism with the master cloclr subsequent to a failure in the voltage of the energizing Current.

It is a further object yof this invention to devise a simplied form of motive device timed electrical impulses. t

It is another object of this invention to Z0 devise a novel form of thermal motive device to actuate the mechanism of an electrical clock, the motive device being operated by a a series of timed electrical impulses.

Further objects ofthis inventionwill appear `from the followingdescription in which I have set'forth the preferred embodiment of my invention. "It is to be understood that the appended claims are to be accorded a range of equivalents consistent with the state of the prior art.

Referring to the drawings:

Figure 1 isa circuit diagram illustrating the system of this invention. y

Fig. 2 is a 4detail showing a clock work mechanism and the thermal motive device of this invention for actuating the same.

f Fig. 3 risa detail in cross section showing the manner in which the resistance wire is mounted asacartridgeunit. p' A Fig. 4 is a plan view of a clock work mechanism shown in Fig. 2, a part of the casing being broken away. Y' v Inthis invention a plurality of dependent clocks are included in a commonelectrical circuit'with a master Clock. Control of the circuit by the master Vclock is effected bythe use of a relay which closes the circuit at regular timed intervals, `say about one minute apart. It is proposed'to employialternating current as a source of current supply i' nating current. for a Clock which Is operated by a serles of in the form of a relay, Winding 16. of'which and the voltage of this current is stepped down for the dependent clocks by individual transformers. In case the voltage 'of the source lfails for some reason or other, the master clock continues to function and stores up the impulses which ordinarily vwould be transmitted to the dependent clocks. i When the line voltage again becomes normal, the stored up impulses are transmitted to the dependent clocks at a relatively rapid rate-tol bring the dependent'clocks'back into synchronsm with the master clock. The motive devicesfor the depeHdentclOCks and for the master-'clock are thermal in their operation andare especially adapted/for use with alter- In the system illustrated in the drawings there are shown a plurality of dependent clocks 10 which are controlled from a master clock 11. The dependent clocks 10 are preferably connected in parallel relation to the conductors 12 andI 13, whichthus form an electrical circuit .including the alternating current supply lines Ll and L27. f The current supplied to each dependent clock is stepped down by means of a small independent transformer 14 as will be presently described. Included in serieswiththis circuit there is a circuit closing device `15, which is preferably is controlled by the master clock. The master clock includes a conventional form of clockwork mechanism 17, being of the type which has a spring motor adapted to be 'wound as by means of rotatable shaft g5 18. This mechanism drives a shaft 19 at a iiXcd rate, and upon this'shaft there is a novel form of circuit interrupter for controlling relay 15, and an impulse storage jdevice. Thus fixed upon the shaft19'so as to revolve therewith, there'is a disc 21 which carries a pin 22. Loosely mounted upon the shaft adjacent to but spaced fromdisc 21, there is a notched wheel 23 which carries fa lug 24 adapted to engage the pin 22.v Interconnecto5 ing the shaft 19 with the notched wheel 28,

lthere is a coil spring`26 which is normally operates with the relatively stationary contact 28. By means of a circuit which includes winding 16, conductors 29, and 3l and the secondary of transformer 32, closing of strip 27 with its contact 28 serves to energize the relay 15. The transformer 32 has its primary connected to lines L1 and L2 and serves to step down the voltage of the current supplied to the relay.

As disc 21 isrotated at a constant rate, contact 27 will close the relay at timed intervals and the rela will similarly close the energizing circuit or the dependent clocks. If the voltage across linesL1 and L2 drops to zero or below a given minimum value, the master clock will continue to operate for a considerable period but the dependent clocks will not operate due to the fact that no current will be supplied to transformers 14. -This is a common occurrence in ordinary 116 volt alternating current lighting systems with which it is proposed to operate this system. If no provision is made for bringing the dependent clocks back into synchronism with the master clock after the line voltage has returned to normal value, the dependent clocks will lag behind the master clock a time interval equal to time period during which the line voltage Cil has failed. I

In order to bring the dependent clocks back into synchronism when the line Voltage returns to normal, it is proposed to store up the impulses which ordinarily would be transmitted and to then transmit these impulses at an increased rate when the voltage again becomes normal. One manner of accomplishing this result consists in controllingthe notched wheel 23 magnetically so tl at when the current falls below normal va ue wheel 23 is prevented from rotating. For eX- ample wheel 23 is movable longitudinallyvof shaft 19 by means of a pivotally mounted shifting lever 36. An armature 37 fixed to. lever 36 is controlled by magnet 38, which is connected across conductors 30 and 3l, or across the output of transformer 32. Adjacent to one face of wheel 23 there is a brake shoe 39 and wheel 23 is normally resiliently urged toward this shoe as by means of spring 41. Also disposed on shaft 19 so as to rotate together with Wheel 23 there is a, gear 42 which connects to a suitable speed governor 43. The conventional form of governor is shown consisting o'f apinion 44- engaging gear 42, the pinion being connected to the ordinary flyballs 46 which in turn control a brake disc 47. Disc 47 cooperates with the ordinary stationary brake shoe 48. Vhen the voltage across lines L1 and L2 is practically normal magnet 38 retains the wheel 23 out of contact with shoe 39 so that it rotates together with disc 21 to operate the spring contact 27. If .the voltage across lines L1 and L2 falls below a value' below which the current supplied to transformers 14 would be insuili- -cient to operate the individual motive devices of the de endent clocks, spring 41 exerts sutlicient orce to throw lever 36 away from magnet 38,l thus causing wheel 23 to engage shoe 39. qWheel 23 will then be held stationary as long as the voltage remains below normal while disc 21 continues to rotate and wind up spring 26. When the voltage returns to normal magnet 38 operating upon armature 37 has sufficient force to withdraw wheel 23 from brake shoe 39, thus permitting wheel 23 to rotate under the tension of spring 26. The governor 43 is arranged so that Wheel 23 may rotate at a much higher rate 'of'speed than disc 21 so'that after a period during which disc 23 has been held stationary, it will rotate to return to its normal position with respect to disc 21, and while returning to this relative position, it will cause relay 15 to transmit to the independent clocks the number of impulses which would normally have been sent if rotation of disc 23 had not been suspended. These stored up impulses are sent out at a much higher rate than the normal rate of impulses so that the independent clocks are brought up into synchronism with the master clock in as short a time as `possible.

4The spring motor lof the clockwork mechanism 11 is kept normally wound by means of an electric motive device controlled by relay 15. One suitable motive device which gives good results when employed with alternating current comprises a ratchet wheel 51 mounted upon shaft 18. Engaging the teeth of wheel 51 there is a check pawl 52 and a ratcheting pawl 53. The ratcheting pawl is pivotally mounted upon one end of a pivoted lever 54. Movement of lever 54 is effected by means of the expansion and contraction of a line resistance wire through which the timed impulses'are passed. For ex'ample there is shown an elongated line resistance wire 55 having its ends connected by means of conductors 56 and 57 to the secondary of step down transformer 58, the primary of this transformer being connected across conductors 12 and 13 so as to be connected to lines L1 and L2 in series with relay 15. One end of wire 55 is secured to a fixed member 59 while the other end is secured to a movable member 61 which abuts lever 54. A compression spring 62 serves as resilient means for tensioning wire 55 while another biasing spring 63 may be provided for urging lever 54 into contact with movable member 61. When an electrical impulse is sent through resistance Wire 55 responsive to closing of relay 15, this wire is heated and expanded to permit compression spring 62 to force lever 54 upwardly to move winding wheel 51 one notch. When the current is interrupted due to opening of relay 15, wire 55 contracts to its original length and compresses spring When the clockwork mechanism is kept Wound by a motive device connected as describedfabove, it will be noted that the samel timing relay which controls the electrical impulses which actuate the dependent clocks, also controls the impulses which keep the clockwork mechanism in wound condition.

While the spring motor of the clockwork. mechanism 17 may be called upon to drive. shaft 19 during the periods when the voltage.

across lines L1 and L2 is below a given minimum value, as soon as this voltage returns to normal valuev the stored impulses which are sent out by relay 15 bring the winding wheel y ample in Figs. 2 to 4'inclusive there is shown clockwork mechanism including the hourl and minute hands 66l and 67 mounted upon concentric shafts 68 and 69 respectively. These shafts are suitably journaled within a frame 71, and fixed u on shaft 69 are a pair of notched wheels 2 and 73. A train of reducing gears 74 interconnect shafts 68 and 69 so that for one complete revolution of-shaft 69, shaft 68 and hour hand 66 will make only one twelfth of a revolution. Mounted upon the pivot pin 76, there is a ratcheting lever 77 which carries a pivoted pawl 7 8, this pawl engaging the teeth of ratchet wheel 72. A pivotally mounted check pawl 79 also-engages the teethofwheel 72 so that shaft 69 is constrained to rotate inf one direction only. The teeth of `wheel7 3 are facedoppositely with respect to the teeth on wheel 7 2. projection 80 secured to lever 77 engages wheel 73 upon movement of lever 77 in order to prevent this`lever from moving wheel 72 ,morethan one notch at-a time. Lever 77 is normally biased toward disengaged position as by means of spring 81.

The thermal device for moving lever 77 is preferably constructed in the form vof av cartridge 82 which may be removed as a unit from the clockwork mechanism. The particular unit shown comprises an elongated tube 83 within which is extended a fine resistance wire'84 having a relatively highl temperature coefficient lof expansion. In one end of tube 83 there is slidably disposed plug86 having an end portion 87 which is adapted to abut a member 88, this member` being mounted upon ratcheting lever 77. On the other end of tube 83 there is a plug 89 to which is secured an insulated terminal conductor 91. One end of wire 84 is secured to the inner end of terminal conductor 91, while the other end is fixed within movable member 86, as by means of a set Yscrew 92.- Mounted upon the frame 71 of the clockwork mechanism there is an internallyl threaded sleeve 93 adapted to receive the threaded portion 94` of tube 83.' The expansion wire 84 is normallyftensioned by means of a `compression spring 96 which is disposed within-the tube 83 and has its ends abutting against the plug i 89 and movable member 86. When the tube has been properly positioned within sleeve 93 to bring the movable member 86 into abutting contact with ratcheting lever 77, an electrical lcurrent or impulse sent through resistance wire 84 causes this wire to be heated 4 and to expand to permit the spring 96 to force lmember 86 outwardly, thus moving lever 77 to notch the wheel 72. When the current is interrupted wire 84 then cools and contracts to withdraw member 86 and return lever 77 to its original position. In practice connection is'l made from the transformer 14 to the tube 83 and terminal conductor 91. Since a motive device` of this kind is not dependent upon a magnetic field, it will operate equally well upon either direct or alternating current.` lIn case the' Wire 84 becomes broken, repairs can be readily made merely by insertmg a new tubular unit. The clockwork mechanism and its motive device are shown as mounted within a suitable casing 97 having a transparent front 98 and the usual clock dial 99.

The operation of the complete system is briefly as follows: Rotation of the notched Wheel 23 by the master clockwork mechanism 17 causes relay 15 to transmitregularly serves to actuate the cl'o'ckwork mechanism of each dependent clock so that all ofthe dependent clocks are kept in synchronism with When the voltage across the master clock. lines Laand L2 falls below a given minimum value below which the current flowing in the individual clocks would bev insuflicient to affect their actuation, motion of notched` wheel 23 is arrested and the impulses are stored until the line voltage returns to its normal value. pendent clocks fail to operate but when the voltage returns to normal value the vstored up impulses are sent out atan increased' During such period the detimed impulses to the7 dependent clocks. v

rate to bring the dependent clocks back into i ing of shaft-19. The use of individual reduc-- ing transformers for the dependent clocks makesit possible to operate the system with a minimum of current consumption, and also makes it unnecessary to employ resistance wires of abnormal length and resistance for the motive devices.

I claim:

l. In a clock system, a master clock, a dependent clock, a circuit interconnecting Said clocks, a source of current included in said circuit, electromotive means operative from recurrent impulses received from said circuit andserving to drive said dependent clock, impulse transmitting means controlled by said primary clock and serving to normally transmit timed recurrent impulses over said circuit to operate said motive means to drive the dependent clock in synchroniSm-With the master clock, and means for transmitting a plurality of relatively rapid impulses over said circuit following a period of failure of said source of current, the number of said rapid impulses being that necessary to bring the dependent clock into synchronism with thev master clock.

2. In a clock system, a master clock, a dependent clock, a circuit interconnecting said clocks, a source of current included in said circuit, electromotive meansy operative .from recurrent impulses received from said circuit and serving -to drive said dependent clock, impulse transmitting means controlled by said primary clock and serving to normally transmit timed recurrent impulses over said circuit to operate said motive means to drive the dependent clock in synchronism With the master clock, means for arresting transmission of such impulses during an interval of failure of said Source of current, and means fortransmitting impulses at a rapid rate following resumption of said source to normal conditions.

`3. In a clock system, a master clock, a de pendent clock, a ymotive device for said dependent clock operative responsive to recurrent electrical impulses, an electrical circuit connected to said motive device, contacts ineluded in said circuit and adapted to be opened and closed during operation of the master clock to supply operating recurrent impulses to the dependent clock, a source of current included in said circuit, and means for arresting opening and closing of said contacts when the voltage of said source falls below1 a given value and for effecting rela-` tively rapid opening and closing of said con.-

tacts to bring both clocks in synchronism when said voltage resumes normal value.

In testimony whereof, I have hereunto set my hand.

MILTON H. SHOENBERG, 

